Keep Your Act Clean: The Importance of Intake and EGR Cleaning on Your TDI

Why does my EGR system and intake manifold become clogged on my TDI?

Volkswagen has been offering a diesel engine option in their US vehicles for around 30 years now. The original 1.5 and 1.6 lumps weren't anything to write home about in terms of power, however when it came to efficiency, they still performed extremely well, often posting numbers close to or even surpassing hybrid vehicles of today. After the 1.6 naturally aspirated diesels had been accepted, the power was raised by upgrading the fuel pump and adding a turbocharger, upgrading the power by nearly 50% to a robust 76 HP, upped from about 54. These engines went through further adaptions with the ECO-diesel in the early 90's, in which the fuel was turned down but the turbo remained, effectively cleaning up the emissions due to the leaned out fuel mixture using the turbocharger.

In the mid- nineties, VW once again upgraded their diesel engine, again using an electronic injection system, based on the gasoline engines EFI (electronic fuel injection) and by increasing the displacement to 1.9L. The TDI (turbo direct injection) monitors the running conditions of the engine using sensors, which improved many of the aspects of their diesel engine including it's ability to easily start in cold weather, overall power output, efficiency and it's emissions. These newer electronically controlled diesel engines complied with EPA's new OBDII regulations, which allowed their emissions to be continuously monitored, and immediately notifying the operator if any problem occured that could possibly affect the emissions of the vehicle.

Of the unfavorable exhaust gases produced by internal combustion engines, NOx (nitrogen oxide) is considerably higher in the diesel engine due to the higher combustion temperatures produced, when compared to it's gasoline counterpart. Due to it's potential to cause health problems, NOx is controlled on both diesel and gasoline engines using a device called an EGR valve, which stands for exhaust gas recirculation valve. At the most opportune time, the EGR valve diverts a portion of the exhaust gases coming out of the engine back into the engine, to be burned again, effectively reducing the amount of overall NOx in the exhaust.

The TDI engine also features a CCV valve, or crankcase ventilation valve. All internal combustion engines have the potential to leak a small portion of unburned fuel mixture by piston rings, into the engine's crankcase. This mixture can also contain a small amount of condensation from the ambient humidity of the intake air. In the crankcase, this mixture is combined with the oil vapors of the engine, produced by the high-speeds of the engine and it's lubrication, engine oil. If unaddressed, these gases could accumulate in the engine eventually cause problems beyond rust and corrosion.

To get clean, you've got to get a little dirty...

An example of a clogged EGR valve.

A clogged intake will limit the engine's power!

A freshly ultrasonically cleaned intake manifold, ready to install!

Cleaned runners on an intake manifold.

Cleaned EGR valve. Note: The EGR plunger has been removed, as this was for a purpose-built race motor.

To fight these potential problems, auto manufacturers have used a CCV (or oil breather on older engines) to direct these gasses back into the intake, to be burned during the combustion process. On the TDI, both the CCV and the EGR valve deposit to a similar area, which is the culprit of the problem. Here, inside the EGR and the intake manifold, these oil vapors combine with the sooty exhaust gases causing an eventual buildup of film, prevelant on the EGR valve, cooler and related piping, and the engines intake manifold. This buildup can become quite extreme, and slowly rob the car of power and efficiency, and has the potential to lead to serious problems should a piece of that buildup fall into the combustion chamber. If unaddressed, the carbon has the potential to damage internal engine components, and even the turbocharger should the carbon survive the combustion process, causing expensive repairs.

Is this EGR problem caused by the use of vegetable oil? Absolutely not! The TDI EGR problem has been a thorn in VW's side since that engine design was implemented. VW's initial solution to the problem was to have an outside company design a machine that would allow them to clean the affected engine components without removal. This solution met with only limited success, leaving only the option to replace your components to the tune of well over 500$. If you are considering a conversion, now would be a great time to clean those components.

Ultimately, the solution to this buildup problem is most easily addressed by periodic maintenance. Checking the EGR and intake is easily done by a visual inspection, by removing one of the intake hoses. A good rule of thumb is to check the intake with each scheduled timing belt replacement, or every 60K miles. The cleaning of these components is a minimal expense, yet a necessary one. Greasecar is fully equipped to take care of these problematic parts. We can remove your EGR valve, EGR cooler, intake manifold and EGR tubes, and have them ultrasonically cleaned, restoring the original operation of your engine, and ensuring it will continue to offer reliable service. Schedule your cleaning today, by calling Greasecar at 413-534-0013.

For more information, Alldata, Identifix, and Motor Age magazine have all written recent tech articles regarding this common and often overlooked issue. All photos in this article were taken from un-converted vehicles.